Sentence-ending period is included in user and channel mentions ("thanks @john." mentions "john.")

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@mayank609 is already working on this.

Since Oct 31, 2026.

  • #43392 by @mayank609 — open

Assessment

Difficulty
2/5
Estimated time
1-3 hours
Newbie friendliness
20/100
Issue type
Bug
Clarity
Clearly specified
Activity status
Stale
Tech stack
typescript
Domain
backend-api-design

Research direction

The issue points to UserMentionDirect, ChannelMention, and UTF8NamesValidation in @rocket.chat/message-parser, and cites tests/mention.test.ts. Read the existing mention tests and inspect how trailing punctuation is parsed. Done means sentence-ending periods are excluded from mentions while the existing username-ending-in-period case is addressed; the issue says a fix and tests are already in a PR.

Written by the indexing model from the issue text.

Description

type: bug
Description

When a message ends a sentence with a mention, the period is parsed as part of the username or channel name.

Input Parsed mention Expected
thanks @john. john. john
see #general. general. general
@john... john... john

! and ? already work as expected (ask @john! mentions john), so only . is affected.

Since Mentions.execute builds message.mentions from the parsed message.md when it exists, the server then looks up a user named john.. As far as I can tell this means the intended user isn't added to mentions and doesn't get the mention notification or highlight.

Steps to reproduce
  1. Send thanks @<existing username>. in a room.
  2. The mention isn't rendered or notified for that user.

In @rocket.chat/message-parser:

parse('thanks @john.');
// MENTION_USER 'john.' instead of MENTION_USER 'john' + PLAIN_TEXT '.'
Cause

UserMentionDirect and ChannelMention use UTF8NamesValidation = $([-_.] / AlphaNumericChar)+, which accepts a trailing ..

Trade-off to discuss

The default UTF8_User_Names_Validation ([0-9a-zA-Z-_.]+) technically allows usernames that end in ., and tests/mention.test.ts currently expects @guilherme.gazzo. to mention guilherme.gazzo.. Dropping the trailing period would change that case. Ending a sentence with a mention seems much more common than a username ending in ., and this matches how Slack, GitHub and Discord handle it, but I'd like a maintainer's view on whether the change is acceptable.

I've opened a PR with a fix and tests.

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